Investigation of Time-Dependent Resistive Switching Behaviors of Unipolar Nonvolatile Organic Memory Devices

Organic resistive memory devices are one of the promising next-generation data storage technologies which can potentially enable low-cost printable and flexible memory devices. Despite a substantial development of the field, the mechanism of the resistive switching phenomenon in organic resistive memory devices has not been clearly understood. Here, the time-dependent current behavior of unipolar organic resistive memory devices under a constant voltage stress to investigate the turn-on process is studied. The turn-on process is discovered to occur probabilistically through a series of abrupt increases in the current, each of which can be associated with new conducting paths formation. The measured turn-on time values can be collectively described with the Weibull distribution which reveals the properties of the percolated conducting paths. Both the shape of the network and the current path formation rate are significantly affected by the stress voltage. A general probabilistic nature of the percolated conducting path formation during the turn-on process is demonstrated among unipolar memory devices made of various materials. The results of this study are also highly relevant for practical operations of the resistive memory devices since the guidelines for time-widths and magnitudes of voltage pulses required for writing and reading operation can be potentially set.